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Date: Tue, 5 Dec 2000 19:48:25 +0000 (GMT)
From: Tigran Aivazian <tigran@veritas.com>
To: Alexander Viro <viro@math.psu.edu>
cc: linux-kernel@vger.kernel.org
Subject: Re: check_lock() in d_move() and switch_names()?
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On Tue, 5 Dec 2000, Alexander Viro wrote:
> > The check for BKL in d_move() and switch_names() seem to be unnecessary as
> > d_move() takes dcache_lock and switch_names() is only called by
> > d_move(). So, if the callers take BKL just for the sake of d_move() they
> > do not need to, but if, for other reasons, then that is fine. In any case,
> > the checks in both functions can be removed, imho. Opinions?
> 
> Tigran, _please_ stop it. d_move() needs BKL. Test in question is a
> sanity check _and_ reminder of that fact, so please leave it in place. 
> Microoptimizations are OK when they make the code cleaner, but here...

Alexander, in one point at least you are wrong. That one point is -- I did
_not_ suggest any optimizations (especially microoptimizations). I was
merely trying to see exactly _why_ d_move() needs a BKL since it takes
dcache_lock which already protects the lists which d_move manipulats. 

You did, however provide useful information, namely the statement "d_move
needs BKL", albeit, without any proof to the truth thereof. So, I'll look
closer and try to find the proof myself.

Thank you,
Tigran

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